| 摘要 |
A double displacement downhole pump for use in oil wells is provided. The pump comprises a body defining a drive cylinder and pump cylinder which are axially-spaced apart. A drive piston is coupled directly to a pump piston by means of a sleeve connector. The sleeve connector is received on a tension member which extends axially through the pump. The tension member acts to counteract deformity of the sleeve connector during use. The advantage of this construction is that it allows virtually unlimited separation distance between the drive piston and pump piston, which in turn allows a virtually unlimited stroke length for the pump.
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